A promising ion-beam-assisted deposition (IBAD) method was developed to improve the salt-water corrosion resistance of NiCoCrAlY-AlSiY coating. During hot salt-water exposure, hydrochloric acid (HCl) was produced when chloride salt, water, and metal oxide reacted with each other, while HCl was also produced when chlorine reacted with water. The as-deposited AlSiY layer exhibited a loose texture accompanied by numerous pore defects, which triggered the multi-scale diffusion of HCl, resulting in the large-area corrosion degradation of the coating texture and the rapid diffusion of the NiCoCrAlY bonding layer. By contrast, the ion-beam-assisted AlSiY layer showed a dense texture that effectively inhibited the inner diffusion of HCl and suppressed the corrosion reactions as well as the diffusion of the NiCoCrAlY bonding layer. The current results confirmed the significant potential of IBAD in inhibiting corrosion damage and diffusion of thermal protective coatings.

To understand the enhanced protection mechanism of CoCrNiAlY–YSZ–LaMgAl₁₁O₁₉ double-layer ceramic coating with aluminum plating, a finite element simulation method was used to simulate the distribution of thermal stress in the coating in all directions. The results show that in the air exposure of the un-aluminized coating, high temperature causes a large radial thermal stress on the surface of the LaMgAl₁₁O₁₉ (LMA) layer, and it increases with the increase in temperature, which is the main reason for the initiation of axial cracks. After arc aluminum plating, the aluminum plating layer effectively inhibited the volume shrinkage of the coating through good adhesion to the coating and internal diffusion; the thermal stress of the coating was considerably reduced; and the CoCrNiAlY–YSZ–LMA coating had an effective enhancement and protection effect. However, there was still a certain amount of shear thermal stress inside the LMA layer, the top of the crack, and the bottom of the crack. This thermal stress caused the initiation of radial microcracks in the LMA layer, which also becomes a risk point for the failure of the aluminum coating.